The present invention relates to a stilbene derivative having excellent electric charge transferring capability and a method of producing the same, and an electrophotosensitive material containing the stilbene derivative, which is used in image forming apparatuses such as electrostatic copying machine, facsimile, laser beam printer and the like.
In the image forming apparatuses, various organic photoconductors having a sensitivity within a wavelength range of a light source used in said apparatuses have been used. These organic photoconductors have widely been used because of easier production than that in the case of a conventional inorganic photoconductor, various selective photosensitive materials (e.g. electric charge transferring material, electric charge generating material, binding resin, etc.) and high design freedom.
Examples of the organic photoconductor include a single-layer type photoconductor wherein an electric charge transferring material and an electric charge generating material are dispersed in the same photosensitive layer, and a multi-layer photoconductor comprising an electric charge generating layer containing an electric charge generating material and an electron transferring layer containing an electron transferring material, which are mutually laminated.
As the electric charge transferring material used in the above organic photoconductor, a stilbene derivative is disclosed in Japanese Patent Kokai Publication Nos. 31773/1975 and 244389/1996.
However, since the stilbene derivative disclosed in the above publications is usually inferior in compatibility with a binding resin and is not uniformly dispersed in the photosensitive layer, electric charges hardly move. Therefore, although the above stilbene derivative itself has high electric charge mobility, when using this stilbene derivative as the electric charge transferring material in the photoconductor, its characteristics can not be sufficiently exhibited. Accordingly, the residual potential of the photoconductor becomes higher and the photosensitivity becomes insufficient.